Former National Security Council head Uzi Arad was recently cleared of allegations, made last year, that he had blurted some terrible security secret. The Shin Bet security service that quizzed him, the Mossad - whose research section Arad once headed - and the attorney general's senior aide, Raz Nizri, all took pains to put the pieces together again.

This is not good enough for Arad, who was deeply offended by the way he was treated by the Shin Bet, his former colleagues in the Prime Minister's Office and Prime Minister Benjamin Netanyahu himself. Represented by attorneys Shlomo Cohen and Eyal Rozovsky, Arad will not let go of his persecutors, whom he suspects of exceeding their authority and abusing their power.

But the troubling question, beyond conniving against a senior official and leadership intrigues, is who will restrain the Shin Bet?

Arad's investigation was triggered by a momentary alarm that gripped Netanyahu over a trifling matter - a situation to which he is prone. In the summer of 2010, the Obama administration worked hard to appease Israel, which feared that President Barack Obama had retracted a long-standing presidential understanding not to infringe on Israel's strategic deterrence. Officials in Washington, D.C., and Jerusalem drafted a letter from Obama to Netanyahu. On the Israeli side it was crafted by Arad.

Some Israelis, not Arad, hastened to expose a marginal civilian-commercial point intended for later publication - that the American side had authorized Israel, as an exception to the rule, to conduct talks on the purchase of nuclear power reactors, even though it is not party to the nonproliferation treaty.

It is doubtful whether the reactors' advantage, in reducing the dependence on fuel and gas, would exceed their harm. See last year's Fukushima disaster in Japan as a case in point; or Iran, Hezbollah and Hamas placing them on their target list.

In the spring of 2010, interested parties had started boasting openly of the reactor innovation. In the summer, some Israelis published this clause from Obama's letter. Gary Seymour, the White House official in charge of arms control and nonproliferation, was angered by the publication and considered canceling a visit to Israel.

The storm died down within days. But meanwhile Netanyahu got alarmed, asked the Atomic Energy Committee for a damage estimate (not from the Defense Ministry's experts on the issue ) and launched a Shin Bet investigation - with the attorney general's approval - but without any supervision over proceedings.

The attorney general usually assigns a supervising attorney for sensitive police inquiries that involve quizzing senior officials, from the prime minister to the chief of staff, and are to determine whether they would be indicted. He does not assign a supervisor to Shin Bet investigations, although not all of them deal with foiling an imminent terror attack or blocking an urgent security breach.

The attorney general, who approves the investigation, is indifferent to the goings-on in the investigations themselves. In his opinion, as Nizri said, the Shin Bet can be relied on not to "invent arguments or a memorandum."

The Shin Bet's most offensive measure during interrogations of senior Israeli officials is to revoke the suspect's security clearance. The law enables the suspect to appeal such a move before a committee headed by a retired district court judge. But the Shin Bet interrogators who terrified Arad did not offer him this option. Afterward, Nizri argued in their name that Arad's clearance had been canceled automatically with the termination of his post in the PMO.

But the state comptroller was troubled to find in the Boaz Harpaz affair - involving a forged document to discredit Maj. Gen. Yoav Galant's chances of becoming chief of staff - that no procedure exists for revoking the security clearance of various has-beens, including prime ministers, defense ministers and Shin Bet chiefs. Some of these ex-officials continue - courtesy of their successors - to be privy to secrets, despite the commercial conflict of interests this involves.

Supervision of the Shin Bet is weak, despite past experience and the failure to operate an ombudsman for interrogees' complaints. The State Prosecutor's Office has been dragging its feet in filling this post for a year and a half, since the decision to transfer the ombudsman's office from the Shin Bet to the prosecution office.

Despite the Shin Bet's lofty statements about "vision," "calling" and "values," it is a power-intoxicated organization of which everyone - even its democratic masters - are afraid. The Shin Bet is by nature a Rottweiler, not a poodle, and if not restrained it will attack, even its owners.

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